Search crews were scouring the waters off the Turks and Caicos Islands on Tuesday, searching for survivors of an overloaded sailboat that hit a reef and capsized.

At least 15 people were pronounced dead in the accident by Tuesday afternoon, but that number could swell as the search continued into the evening hours.

An estimated 200 people were on the vessel when it struck the reef at about 2 p.m. Monday. But some reports said the boat flipped on Sunday night, and a survivor told The Associated Press that the accident occurred as the migrants onboard attempted to elude a police patrol.

The area is a common transit zone for Haitians looking for a new life in the U.S.

So far, rescuers have pulled 113 Haitian survivors from the reefs, but up to 70 people are still missing. Crews are now scanning a massive search area of more than 4,000-square-kilometres.

"We're really hoping we can find as many people as possible," Petty Officer 1st Class Jennifer Johnson, a U.S. Coast Guard spokeswoman in Miami, told the AP.

"However, as time goes by, it becomes less and less likely because of exposure and fatigue."

Turks and Caicos authorities sent a number of small boats to the scene to help with the rescue efforts. A U.S. Coast Guard cutter searched the waters overnight for survivors.

A helicopter and jet joined in the search at the break of dawn, but rescuers said any potential survivors would have had to battle 2-metre waves and stiff winds.

The boat had reportedly been at sea for three days when passengers spotted a police vessel. In an effort to hide, the boat was accidentally steered onto a reef and capsized.

"We saw police boats and we tried to hide until they passed," said survivor Alces Julien, who spoke to the AP at a hospital in the Turks and Caicos. "We hit a reef and the boat broke up."

But Deputy Police Commissioner Hubert Hughes said police were not pursuing the sail-powered vessel, and were involved only as rescuers.

"They were travelling in waters that are quite dangerous if you don't know the area quite well," he said.

Some survivors later accused the police of ramming their boat.

Louis Harold Joseph, who is the Haitian ambassador to the Bahamas, said the accident illustrates the nation's deep-rooted problems.

"The rate of growth right now in Haiti is not enough to provide jobs for a great number of people and prevent them from risking their life," Joseph said.

Haitians have tried to escape by sea in the past, hoping for a new life after leaving behind their impoverished homeland. Often the means of escape is a rickety, overcrowded boat.

This past May, a pregnant woman and eight others were killed when a boat carrying about 30 Haitian migrants overturned near the Florida coastline.

In May 2007, a small vessel carrying more than 160 migrants capsized as they sailed past the Turks and Caicos Islands. Authorities said 78 people survived that shipwreck and that some of the survivors were attacked by sharks.

With files from The Associated Press